In various medical situations there is a need to divert blood from the circulatory system and then later reintroduce the removed blood back into the circulatory system. For example, patients with renal problems may require hemodialysis to stay alive. In such a situation, due to the fact that the patient's kidney is not functioning properly to remove biological waste from the patient's circulatory system, the blood must be removed from the patient and treated outside the body to remove the biological wastes, and then returned to the circulatory system. A common approach is to introduce a dual lumen catheter into a blood vessel within the patient's body. The catheter has one lumen for removing blood and another lumen for reintroducing the processed blood back into the patient's circulatory system. The dual lumen catheter allows access to the circulatory system to be established through a single insertion site, and therefore minimize surgical trauma and decrease potential for infection and other complication.
For example, a dual lumen catheter may be inserted into the patient's superior vena cava via the subclavian vein, external jugular vein or the internal jugular vein. A small incision is made to locate the desired vessel for insertion of the catheter. A second incision is made at the desired exit site of the catheter, usually in the area between the nipple and sternal border. A tunneler may then be used to tunnel the distal section of the catheter from the exit site to the vessel entry site. The surgeon locates the desired vein and inserts the distal end of the catheter into it. The surgeon then advances the catheter along the vessel until the distal end of the catheter is inside the superior vena cava. Micropuncture sets, syringes, microinstroducer guidewires, and other surgical tools for catheter placement, which are well known to one of ordinary skill in the art, may be implemented to facilitate the catheter insertion and advancement process. After the catheter is inserted inside the superior vena cava, the position of the distal tip of the venous catheter may then be adjusted. For example, some surgeons prefer to position the distal tip of the catheter just above the right atrium. Once the catheter is put in place, the proximal end of the catheter may then be connected to a hemodialysis machine, which may then extract blood from the patient's body through the catheter, process the blood, and then return the processed blood back into the patient's body through the implanted catheter.
Examples of various catheters for extracting and/or introducing blood into a patients circulatory system are disclosed in U.S. Patent Application, Publication No. 2002/0188167 A1, entitled “MULTILUMEN CATHETER FOR MINIMIZING LIMB ISCHEMIA” published Dec. 12, 2002; U.S. Patent Application, Publication No. 2003/0032918 A1, entitled “CATHETER” published Feb. 13, 2003; U.S. Pat. No. 4,563,180, titled “HIGH FLOW CATHETER FOR INJECTING FLUIDS” issued to Jervis et al., dated Jan. 7, 1986; U.S. Pat. No. 4,863,441, titled “VENOUS RETURN CATHETER” issued to Lindsay et al., dated Sep. 5, 1989; U.S. Pat. No. 5,616,137, titled “LOW VELOCITY AORTIC CANNULA” issued to Lindsay, dated Apr. 1, 1997; U.S. Pat. No. 5,643,226, titled “LOW VELOCITY AORTIC CANNULA” issued to Cosgrove et al., dated Jul. 1, 1997; U.S. Pat. No. 5,685,865, titled “LOW VELOCITY AORTIC CANNULA” issued to Cosgrove et al., dated Nov. 11, 1997; U.S. Pat. No. 5,769,828, titled “TWO-STAGE VENOUS CANNULA WITH EXPANDABLE REINFORCING MEMBER” issued to Jonkman, dated Jun. 23, 2998; U.S. Pat. No. 5,989,206, titled “APPARATUS AND METHOD FOR THE DIALYSIS OF BLOOD” issued to Prosl et al., dated Nov. 23, 1999; U.S. Pat. No. 6,280,423 B1, titled “HIGH FLOW RATE DIALYSIS CATHETERS AND RELATED METHODS” issued to Davey et al., dated Aug. 28, 2001; U.S. Pat. No. 6,387,087 B1, titled “AORTIC CANNULA” issued to Grooters, dated May 14, 2002; U.S. Pat. No. 6,540,714 B1, titled “BLOOD VESSEL CATHETER issued to Quinn, dated Apr. 1, 2003; and U.S. Pat. No. 6,582,409 B1, titled “HEMODIALYSIS AND VASCULAR ACCESS SYSTEMS” issued to Squitieri, dated Jun. 24, 2003; each of which is incorporated herein by reference in its entirety.
Although a dual lumen hemodialysis catheter has various advantages, there may be problems associated with some dual lumen designs, such as recirculation of blood. Because the outflow port(s) and inflow port(s) are both located at the distal section of the catheter, a portion of the processed blood exiting the outflow port may be recaptured by the suction at the inflow port and then processed again. If a large amount of blood is being recirculated and redundantly processed, the efficiency of the hemodialysis process may be significantly decreased. The amount of recirculation may also be affected by turbulence and various fluid dynamics at the distal end of the catheter due to the environment surrounding the distal portion of the catheter.
Therefore, a catheter that is configured to decrease recirculation of blood flow may provide substantial benefits, such as improving the efficiency of the hemodialysis treatment process and decreasing treatment time for the patient. Furthermore, a catheter tip designed to minimize the outflow fluid's impact on the existing flow dynamics of the normal circulatory flow may also be desirable. In addition, a catheter tip having a low fluid outflow profile (e.g., low flow velocity exiting the catheter) may be implemented in various other medical applications where low velocity fluid outflow from a catheter is desired.